AB0799 Anatomical abnormalities of the lower lumbar spine do not change the course of non-radiological axial spondyloarthritis
Authors: D. Becker-Capeller, S. Kapsimalakou
Journal: Annals of the Rheumatic Diseases (2022)

Background Diagnosing early spondyloarthritis (SpA) is crucial for effective therapeutic intervention. Magnetic resonance imaging (MRI) helps us to diagnose non-radiographic SpA (nr-ax SpA) in an early stage according to the criteria of the imaging arm of the Assessment of Spondyloarthritis International Society (ASAS) classification. Diagnosis of sacroiliitis using MRI has limitations because of the lack of specificity and sensitivity. Several differential diagnoses are well known and should be considered 1 . In our daily practice, anomalies of the lower lumbar spine and the sacrum, such as spondylolysis, dysraphia, or assimilation joints, are often found to be accompanied by changes in the sacroiliac joints (SIG) corresponding to sacroiliitis. Objectives To investigate the presence of anatomical anomalies of the lower lumbar spine in our cohort of early diagnosed nr-ax SpA patients fulfilling the criteria of ax SpA and show if they cause a difference in the outcome. Methods Patients (n = 56, age &lt; 45 years, symptom duration 3– 24 months) recently diagnosed with sacroiliitis using MRI and meeting the ASAS criteria for axial SpA were followed-up for 2 years 2 . We retrospectively analyzed the anatomic anomalies of the lower lumbar spine on MRI and, if available, on radiograph images. Results MRI on t0 revealed that 15 (26.7%, one female and 14 males) of 56 patients had anatomical anomalies of the lower lumbar spine, indicating bone marrow edema with clinical ax SpA according to the ASAS classification criteria. Spondylolysis, assimilation joints, and dysraphia were found in 4 (7.1%), 7 (12,5%), and 7 (12.5%) patients, respectively. The presence of HLA-B-27 and assessment results (CRP-ASDAS and BASDAI, BASMI) were similar to patients without the mentioned anatomical anomalies. Patients with spondylolysis and dysraphia of the lower spine and those without anomalies displayed similar progression of MRI findings between t0 and t2. Conclusion In addition to the well-known noninflammatory causes of sacroiliitis, such as pregnancies or intensive sporting activity, anatomical peculiarities could not be considered noninflammatory reasons. Contrary to the latest literature 3 , they are not responsible for non-specific sacroiliitis. No difference in the development to axial SpA was observed when patients with and without anatomical changes were compared. References [1]de Winter J, de Hooge M, van de Sande M, et al. Magnetic Resonance Imaging of the Sacroiliac Joints Indicating Sacroiliitis According to the Assessment of SpondyloArthritis international Society Definition in Healthy Individuals, Runners, and Women With Postpartum Back Pain. Arthritis Rheumatol. 2018 Jul; 70 (7):1042-1048. [2]SpA.47 (DGRH Congress 2021 virtuell Posterwalk) Is the course of newly diagnosed axial spondyloarthritis more aggressive than previously thought? Becker-Capeller,D et al. [3]Campos-Correia, D., Sudoł-Szopińska, I., &amp; Diana Afonso, P. Are we overcalling sacroiliitis on MRI? Differential diagnosis that every rheumatologist should know - Part I. Acta reumatologica portuguesa 2019, 44(1), 29–41. Disclosure of Interests Detlef Becker-Capeller Grant/research support from: Research support by Novartis, Smaragda Kapsimalakou: None declared